This invention relates generally to mattress foundation structures and more particularly to a box spring assembly of a type which utilizes non-coil springs. Box spring assemblies of this general type have been known since 1964, the first such spring assembly being disclosed in U.S. Pat. No. 3,286,281. Subsequently issued patents disclosing the same general type of box spring assembly are: U.S. Pat. Nos. 3,487,480; 3,506,987; 3,574,240; 3,574,241; 3,665,529; 3,680,157; 3,755,833; 3,824,639; and 3,852,838. Box spring assemblies of the general type shown in the above list of patents, all of which are assigned to the assignee of this application, are advantageous with respect to the conventional box spring assemblies using coil springs because they provide a desired stiffer foundation of the mattress and contain a reduced amount of wire. These box spring assemblies are also advantageous from the standpoints of prolonged service life, ease of assembly and cost of manufacture.
Additional box spring assemblies of this general type are shown in U.S. Pat. Nos. 3,596,299; 3,722,013; 3,825,960; 3,833,948; 3,835,485, 3,869,740; 3,990,121; and 4,000,531.
The present invention provides a box spring assembly which utilizes a different spring from the formed wire springs utilized in the patented box spring assemblies discussed above. The spring in the present box spring assembly is a stiffer spring than springs heretofore used, this increased stiffness being an inherent feature of the spring achieved by virtue of the spring configuration. Furthermore, this increased stiffness is achieved without any reduction in the usual height of the box spring assembly, and enables the production of firmer box spring assemblies from less raw material.
It is an object of the present invention, therefore, to provide an improved box spring assembly having increased resistance to bedding loads and requiring a decreased amount of raw material relative to prior art structures.